jessica doyle has what you need to know to protect your computer from ransomware. >> reporter: steve merrifield owns a high end sporting goods shop. after 27 years in business he'd been preparing to sell it. all of the records for potential buyers stored on his computer server. so merrifield was more than concerned when he realized all his data had been frozen. >> the last words i remember is this is not good. this is not good. >> reporter: it turned out hackers had taken control of his machine and flashed a message. for $3,000 merrifield could have his data back, but it didn't stop there. he'd have to fork over an additional $1,000 for each week he didn't comply. this crime is so pervasive it prompted the fbi to put out a warning. the bureau says it's getting dozens of ransomware complaints each day. >> it's one of the more destructive pieces of malware because they'll encrypt those files. if you don't pay, they can just delete them. >> reporter: bruce snell is with the security computer firm mcafee and says the hackers use such complicated methods it's virtually impossible to recov